_____ has been introduced to the students to help them make progress.

The minister said, “We are ready for discussions with any legal parties，but we’ll never ________ with criminals.”[ ]

reserves are very important forpreserving many animals and plants, which would _______ run the risk ofbecoming extinct

He was left _____, with no one ____ after him.

His aunt wants to have him _______ the radio, but he has had it ______ already.